1. Field of the Invention
The invention is related to the field of magnetic recording head fabrication, and in particular, to improved methods of fabricating a read sensor which involve using a chemical mechanical polishing (CMP) process with a patterned conductive CMP protective layer for sensor stripe height patterning.
2. Statement of the Problem
Magnetic disk drive systems typically include a magnetic disk, a magnetic recording head having read and write elements, a suspension arm, and an actuator arm. As the magnetic disk is rotated, air adjacent to the disk surface moves with the disk. This allows the magnetic recording head (also referred to as a slider) to fly on an extremely thin cushion of air, generally referred to as an air bearing. When the magnetic recording head flies on the air bearing, the actuator arm swings the suspension arm to place the magnetic recording head over selected circular tracks on the rotating magnetic disk where signal fields are written to and read by the write and read elements, respectively. The write and read elements are connected to processing circuitry that operates according to a computer program to implement write and read functions.
The magnetic recording head is typically produced using thin-film deposition and patterning techniques. The magnetic head reader fabrication involves two separate patterning processes. One process defines the stripe height of the read sensor, while another process defines the track width of the read sensor. In particular, the several material layers which make up a read sensor for a magnetic reader are typically formed by depositing full film sensor layers of the required materials on a wafer substrate, depositing and patterning a masking layer over the sensor layers to form a mask structure, etching the exposed portion of the sensor layers around the mask structure, and then removing the mask structure.
The mask structure is removed using a CMP assisted lift-off process. CMP protective layers (also called CMP stop layers) are deposited between various layers of the fabricated structure to protect other layers, such as sensor layers and insulation during the CMP lift-off process. These protective layers are then removed using another etching process (e.g., reactive ion etching or ion milling).
Problems are encountered in the prior art process because alumina bumps or fencing may occur at edges of sensor after the stripe height definition process. This added topography may cause shield shorts and sensor shunt subsequent to the track width definition process because the insulator layer is not fabricated flat with the read sensor. It is evident from the above discussion that improved solutions are needed for fabricating magnetic readers using new processes.